Hi and welcome
It is always best if you have the option to let any piggies meet before adopting, so they can decide whether they get on or not. With boars, rescue dating under expert supervision has shown that it takes on average about 1-3 introductions to find Mr Right; with very dominant and hormonal teenage boars this can take more attempts. The vast majority of boars can find a character companion at any age of their lives. With boars, an age difference is often of advantage as that means that only one boar is hitting a teenage hormone spike at any given time and not both together. It can still not fully guarantee that they will make it together to hormonally settled adulthood, but it considerably ups your chances.
Our recommended good standard UK rescues locator:
Guinea Pig Rescue Centre Locator
Recommended rescues in some other countries:
Guinea Lynx :: Rescue Organizations
If you do not have the change to date your boy at a rescue, then you have to have a plan B in case things don't work out. Most often (especially if you have to commit before you can set up an introduction), this means splitting the cage, so that the boars each have their own territory but they can interact or stimulate each other through the bars.
Since good standard rescues that offer dating are not evenly spread over the world, it very much depends on whether you can get to one or have to make the best of your local options. It would help us a lot helping you most efficiently if you please added your country, state/province or UK county to your details since we have members from all over the world. Please click on your username on the top bar, then go to personal details and scroll down to location. this makes it appear in every post you make and allows us to tailor any advice to what is available, doable and relevant for straight away. Thank you!